Large wind turbines are characterised by two important features: (a) they rotate very slowly and (b) they operate intermittently because the wind resource itself is intermittent. Because of the low rotational speeds, the machines which collect the mechanical power from wind turbine rotors must deal with very high torques and this drives up costs. Gearboxes are used in most cases to increase rotational speed before the power is driven into an electrical generator but the gearboxes themselves still have to deal with the large input torque and this causes them to be both expensive and relatively unreliable.
The present invention proposes a system including a rotating machine which operates to absorb the shaft-power directly from a wind turbine by compressing some compressible fluid adiabatically (or nearly adiabatically) to some relatively large pressure ratio such that a significant temperature rise occurs. The compressible fluid is already at a high pressure before it is compressed further by the wind turbine. That pressure would certainly be upwards of 3 bar and in most practical implementations it would be upwards of 20 bar. The would normally be achieved by keeping the working fluid in a closed-circuit with the lower-pressure part of that closed-circuit still being well above atmospheric pressure.